Image: Mature couple calculating expenses © Abel Mitja Varela, the Agency Collection, Getty Images

Comparing the fortunes of U.S. retirees with their counterparts in other wealthy nations can be challenging, given differences in public and private benefit programs, the age at which citizens leave the workforce, and various pension reforms of recent years.

Generally, though, many economists view public retirement benefits in the United States as less generous than those in other wealthy nations.

The gaps may be narrowing, though, as other countries -- many of which have long had younger retirement ages -- seek to adjust their systems.

"There's a much richer support network in Europe than there is here," says Jonathan Gruber, a professor of economics at the Massachusetts Institute of Technology.

U.S. Social Security Insurance benefits typically replace less than half the income Americans earned on the job, while in Europe, similar benefits often account for at least two-thirds of pre-retirement income, says Gruber.

"We always are neck and neck with the United Kingdom, but other than the U.K., I think we are among the stingiest," adds Alicia Munnell, the director of the Center for Retirement Research at Boston College.

U.S. support for retirees remains below the average for its fellow Organisation for Economic Co-operation and Development member countries at every income level, says Munnell.

US ranking in OECD study

In addition, U.S. public pension spending amounted to 6% of gross domestic product in 2008, less than the 7% average for all OECD countries.

National comparisons depend in part, however, on whether public or private pensions are considered, and on which aspects of retirement benefits are measured.

Among the 34 member OECD countries, the net replacement rate -- retirement income as a percentage of pre-retirement income -- for an average earner is 50% from public pensions alone and nearly 68% when mandatory private pensions are included, according to a 2011 OECD report.

The United States slightly trails the 50% average for public pensions only, at 47.3%, the report showed.

Austria's rate was nearly 90%, Italy's 72%, Hungary's 62%, Portugal's 70%, Germany's 56%, Spain's 85%, France's more than 60%, the United Kingdom's more than 37%, Denmark's 33%, Luxembourg's 94% and the Netherlands' 33.1%. Japan's public pension replacement rate is 40%, Korea's 47.5%.

The United States has no mandatory private pensions. In some of the countries that do, such plans significantly boost the income replacement rate.

Australia's replacement rate, for instance, is 59%, counting public and mandatory private pensions. Denmark's is 90%, Hungary's is 106% and the Netherlands' almost 100%.

Replacement rates assess benefit levels at retirement. The OECD report also measures gross pension wealth -- the value of lifetime flow of retirement income -- and found that average-earning men in member countries received 9.6 times annual earnings, while women, because of longer life-expectancy rates, received 11.1 times annual earnings.

The United States lagged in both measures, with 5.8 times annual earnings for men and 6.8 for women. Countries with higher-than-average gross pension wealth include Spain, Switzerland, Saudi Arabia, Argentina, the Netherlands, Greece, Iceland and Luxembourg.

In another measure, the OECD took weighted averages of various indicators and found the pension level for men across the 34 member countries is 55.3% of economy-wide average earnings. The U.S. figure is 37.5%.

US gets a 'C' grade

The 2011 Melbourne Mercer Global Pension Index, released last fall, compared countries' retirement income systems while acknowledging the complexities in doing so.

Countries were graded on a scale from A (the best) to E (the worst), and no country received an A or an E. The United States, along with France, Singapore, Brazil, Poland and Germany, received a C.

A country given a C has "a system that has some good features, but also has major risks and/or shortcomings that should be addressed," the report states. "Without these improvements, its efficacy and/or long-term sustainability can be questioned."

The United States ranked close to average among 16 countries in adequacy of benefits provided and above average in sustainability, the likelihood that the system can maintain the benefits in the future. It fell short, however, on a sub-index focused on the private sector pension system.

The U.S. could take steps for a better score, the report said, including raising the minimum benefit for low-income retirees, improving benefits vesting and further limiting access to funds before retirement.

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